Convection heating assisted engine-off natural vacuum test

摘要

Methods and systems are provided for conducting an engine off natural vacuum test in a vehicle in order to indicate the presence or absence of undesired evaporative emissions. In one example, a vehicle fuel system and evaporative emissions system are sealed from atmosphere, and responsive to a pressure increase below an expected threshold, the fuel system and evaporative emissions system are actively pressurized via circulating hot engine coolant to a heater core and blowing hot air through the vehicle cabin to the fuel system via a three way ventilation valve in the rear of the vehicle. In this way, false failures of EONV test procedures due to environmental factors and vehicle operator drive habits may be reduced, and unnecessary engine service may be avoided.